Nitrated polymers with saturated hydrocarbon backbone

ABSTRACT

Graft copolymers are prepared in a two-stage process by first reacting, for example, 1,2-polybutadiene or an ethylene/propylene/alkylidene norbornene terpolymer with dinitrogen tetroxide to form a nitrated backbone polymer having incorporated therein nitro and nitrite functions which serve, in the second stage of the process, as sites for the subsequent graft copolymerization of an acrylate monomer.

United States Patent [191 Lachowicz et al.

[ NITRATED POLYMERS WlTl-l SATURATED HYDROCARBON BACKBONE [75]Inventors: Donald R. Lachowicz. Fishkill:

Charles B. Holder, Wappingers Falls. both of NY.

[73] Assignee: Texaco Inc.. New York, NY.

[22] Filed: Jan. 22, 1973 [2!] Appl. N0.: 325,470

Related US. Application Data [63] Continuation of Scr. No. l48.l33 May28. 1971.

[52] US. Cl. 260/80.78: 260/94.7 N; 260/877; 260/878; 260/879 [51] Int.Cl C08f l5/40; C08f 17/00 [58] Field of Search 260/877. 94.7 N, 80.78

[56] References Cited UNITED STATES PATENTS 3583.961 6/197] Magay260/947 N Apr. 22, 1975 3.75l 522 8/1973 Lachowicz ct al 260/877 3.75 l.523 8/1973 Lachowicz ct al 260/877 FOREIGN PATENTS OR APPLICATIONS22l.8l4 6/l962 Austria 260/877 Primary E.\'uminer--Murray TillmanAssistant E.\'aminerRichard B. Turer Attorney. Agent. or Firm-Thomas H.Whaley; Carl G. Ries [57] ABSTRACT 6 Claims, N0 Drawings NITRATEDPOLYMERS WITH SATURATED HYDROCARBON BACKBONE This is a division. ofapplication Ser. No. 148.133. filed May 28, l97l.

BACKGROUND OF THE INVENTION l. Field of the Invention This inventionrelates to graft copolymers and. in particular, to the grafting of anacrylate onto a backbone chain of a dissimilar polymer.

2. Description of the Prior Art The preparation ofa wide variety ofgraftcopolymers has been described in the art. For example. graft copolymerscan be prepared as described in US. Pat. No. 3.507.932 by oxidizing amethacrylic homopolymer. such as isopropyl methacrylate. with air toform a hydroperoxide derivative and then reacting the said derivativewith a high molecular weight methacrylate ester thus forming a graftcopolymer. Prior to this invention. however. no process existed forpreparing a graft copolymer of an acrylate with a backbone polymer. suchas a l.2-polybutadiene. in which a nitrated intermediate product formcdby reacting the l.2-polybutadiene with dinitrogen tetroxide is furtherreacted and polymerized with a acrylate monomer.

One object of this invention is to provide a process for preparing graftcopolymers by copolymerizing an unsaturated hydrocarbon polymerpreviously treated with dinitrogen tetroxide to form reactive sitestherein. with an acrylate monomer.

Another object of this invention is to graft an acrylate monomer to adissimilar backbone polymer while avoiding crosslinking.

BRIEF SUMMARY OF THE INVENTION In the process of this invention graftcopolymers are prepared by:

A. contacting a backbone polymer having a saturated hydrocarbon chainportion and a plurality of pendant hydrocarbon groups each containing amoiety of the formula:

l IO 48 wherein R and R are independently selected from the groupconsisting of hydrogen and alkyl of from 1 to 16 inclusive carbon atomswith dinitrogen tetroxide to form a nitrated intermediate backbonepolymer product having incorporated therein nitro and nitrite (i.e..ONO) groups. and

B. reacting said nitrated intermediate backbone polymer product with anacrylate of the formula:

RC cn -d-cooa wherein R" is hydrogen or alkyl of from 1 to 3 inclusivecarbon atoms and R" is alkyl of from 1 to inclusive carbon atoms. toform a graft copolymer.

The thermoplastic copolymers of this invention. which can be extruded ormolded. can be utilized to prepare sheet. rod. parts for appliances.etc. A wide variety of glass and asbestos fiber reinforced plasticcompositions which exhibit excellent mechanical properties can beprepared using the copolymers of this invention.

DETAILED DESCRIPTION OF THE INVENTION First Stage In the first stagereaction, the backbone polymer is contacted with dinitrogen tetroxide(sometimes after prepurging the reaction system with an inert gas. suchas nitrogen. to remove oxygen) to form a nitrated intermediate polymericproduct containing both nitro and nitrite functions. The exact structureof the nitrated intermediate polymeric product formed in the first stageis not known; however. in the resulting product the nitro and nitritegroups form on either olefinic carbon when both of the latter have thesame number of hydrogen atoms attached. and when the olefin group isterminal. the nitro group attaches itself to the terminal olefiniccarbon. Further. it is known that in a substantial number of therecurring units of the backbone polymer a nitro group adds on to each ofthe olefinic carbon atoms.

The intermediate polymeric compound. i.e.. the nitrated backbone polymerformed in the first stage of the process of this invention whendinitrogen tetroxide is reacted with. for example. a LZ-poIybutadiene isbelieved to contain recurring units of the formula:

c n-(fir O2N-CH2 HC-ONO M iii: are; p ts -tin ir -int while backbonepolymers having. for example. recurring S-methylene-Z-norbornene units.yield intermediate polymeric products believed to contain units of theformula:

no; 7 n0 m ,t. ,t.

and

The formed nitrated backbone polymer product can be recovered from thereaction mixture at the conclusion of the first stage reaction. ifdesired. by stripping off the solvent.

The reaction temperature employed is advantageously between 30 and 20C.Higher reaction temperatures tend to facilitate the decomposition'of thenitrated product and at temperature below the prescribed range thedinitrogen tetroxide will not function due to its inability todissociate into monomeric nitrogen dioxide.

The amount of dinitrogen tetroxide utilized in the first stage which canbe varied over a wide range gener-' ally will be from about 0.00001 to0.01 mole per gram of the backbone polymer charged to the reactor: theactual amount employed depends on the C=C equivalents/gram of backbonepolymer desired to be reacted. The dinitrogen tetroxide may beintroduced into the reactor in liquid form although preferably it isadded as a gas and usually in admixture with an inert gas such asnitrogen, argon, etc. The reaction time is normally between about V2 andhours although longer or shorter periods may be employed.

It is to be noted that the nitrating agent, dinitrogen tetroxide, isactually an equilibrium mixture of dinitrogen tetroxide and nitrogendioxide with the equlibrium being driven to essentially 100% nitrogendioxide at 140C. Under advantageous conditions, the nitrating agent isnormally introduced into the reaction system at a rate of between about0.002 and 0.2 gram/minlgram of backbone polymer; however. the actualrate depends in large measure upon the rate of heat removal from thereaction system. To promote contact of the reactants in the first stage,the reaction is desirably carried out under conditions of agitation inthe presence of an inert liquid diluent, for example. inert liquidshaving a boiling point between about and 100C, such as n-hexane,n-heptane, carbon tetrachloride and diethylether.

Backbone polymers having recurring units of the formula:

wherein R and R have the same meaning as previouslydefined are referredto herein as norbornene polymers.

Norbornene polymers useful as backbone polymers in this inventioninclude homopolymers prepared, for example from the5-alky1idene-2-norbornenes such as 5-methylidene-Z-norbornene (alsocalled 5-methy1ene- Z-norbornene), 5-ethy1idene-2-norbornene,5-isobutylidene-Z-norbornene, 5-n-heptylidene-2- norbornene,5-n-heptadecylidene-2-norbornene, 5-ntridecylidene-Z-norbornene, etc.Mixtures of the homopolymers may be employed, if desired. Suchhomopolyrners can be prepared by contacting a solution of the5-alkylidene-2-norbornene in benzene with a solution of a catalystcomprising titanium tetrachloride and lithium aluminum tetraheptyl inwhich the mole ratio of the titanium tetrachloride to the lithiumaluminum tetraheptyl is more than one as more completely denorbornenesare highly useful as backbone polymers in the process of this invention.These polymericmaterials are copolymers of ethylene, at least onealpha'olefin having the structure:

where R is a C -C alkyl radical and a 5-a1ky1idene-2- norbornene, thesaid terpolymer having an iodine numher between 2 and and containing byweight about 20 to 76.4 percent RCH=CH monomer units, and about 3.6 to20 percent S-alkylidene-Z-norbornene monomer units.

Representative examples of such terpolymers include:ethylene/propylene/S-methylidene-2- norbornene;ethylene/propylene/S-ethylidene-2- norbornene;ethylene/propylene/S-isobutylidene-Z- norbornene;ethylene/propylene/S-n-hepty1idene-2- norbornene;ethylene/1-butene/5-heptylidene-2- norbornene; thylene/ l-butene/5-ethy1idene-2- norbornene; ethylene/1-butene/5-n-decylidene-2-norbornene; ethylene/4,4-dimethyl-l-hexene/S- between 20 and C atatmospheric, subatmospheric, or superatmospheric pressure and in theabsence of catalyst poisons such as oxygen, water, and carbon dioxide.

A second group of backbone polymers which are highly useful as startingmaterials in the process of this invention include polymers havingrecurring units of the formula:

wherein R", R and R" are independently selected from the groupconsisting of hydrogen, and alkyl of from 1 to 16 carbon atoms. Examplesof useful backbone polymers of this type include polymers havingrecurring units as shown below:

Hz 15H: (1,2-po1ybutadiene) (3,4-polyisoprene) The 1, 2-polydienes, suchas the 1.2-po1ybutadienes.

can be formed in a variety of ways well known in the Second Stage 1n thesecond stage. the grafting of acrylate monomer takes place at the siteof nitrite (-ONO) attachment through the mechanism of a free radicalpolymerization. The nitrated intermediate polymer product formed in thefirst stage thus provides not only the sites for the graftpolymerization but also the free radicals necessary to initiate thepolymerization of the acrylate monomer.

After the first stage reaction has been completed and the unsaturatedpolymer having nitro and nitrite groups incorporated therein has beenformed, and if the system previously had not been placed under an inertatmosphere an inert purge gas such as nitrogen, preferably, is passedthrough the reaction mixture and continued until any oxygen has beenremoved. The acrylate monomer, which may be dissolved in an inertsolvent such as ether, n-hexane or benzene, etc. if desired, is thenadded to the polymer solution after the monomer or its solution has beenpurged with an inert gas.

Useful acrylate monomers have the formula:

en ma-coon wherein R is hydrogen of alkyl of from 1 to 3 inclusivecarbon atoms as exemplified by methyl. ethyl, propyl and isomersthereof. and R is alkyl of from 1 to 30 inclusive carbon atoms asexemplified by methyl, ethyl, propyl, butyl, pentyl. hexyl, oxtyl,nonyl. decyl. undecyl, hexadecyl. heptadecyl, octadecyl, nonadecyl.eicosyl. docosyl. pentacosyl. and isomers thereof. Mixtures of theseacrylates may be employed. if desired.

1n the second stage. in which graft copolymerization takes place, thereaction mixture is heated to decompose the nitrite sites in thebackbone polymer. Generally the reaction mixture is heated to atemperature of from about 35 to about 175 C and. preferably. at atemperature of about to about C. The second stage reaction may beconducted under refluxing conditions. Heating is continued until thedesired degree of graft polymerization has been accomplished. The courseof the reaction can be followed by measurement. for example. of therefractive index of the mixture or by determining some other easilymeasurable physical property.

The extent of the grafting achieved is directly dependent on the extentof the nitrite formation. One skilled in the art can prepare the desiredgraft copolymer by carefully selecting the necessary reactionconditions, such as time, temperature, etc. in the first and secondstages of the process of this invention.

Recovery of the product from the reaction mixture can be accomplished bya variety of methods well known in the art such as by the addition ofmethanol or acetone to precipitate the product which can be recovered bydecantation, centrifugation, filtration. etc. and the crude polymer canbe redissolved in a suitable solvent such as chloroform. benzene ortoluene, etc, and reprecipitated in purified form by addition ofmethanol or acetone to the polymer solution. Fractional precipitationmay be utilized to identify the final polymer as a true graft polymer ofthe backbone polymer and the acrylate.

A relatively small amount of dinitrogen tetroxide should be used in thefirst stage when backbone polymers of theethylene/propylene/S-ethy1idene-2- norbornene type is employed (i.e.about 0.00001 to about 0.001 mole of dinitrogen tetroxide/g of polymeror less.

The backbone polymers utilized in forming the novel graft copolymers ofthis invention generally will have molecular weights of from about 5000to about 200,000 or more and, preferably, from about 10,000 to about150,000. The final graft copolymer products will have molecular weightsof from about 6500 to about 1.000.000 or more and, preferably, fromabout 15,000 to about 250,000.

Generally, the backbone polymer will make up about 5 to about 80 and,preferably, from about 10 to about 40 percent by weight of the finalgraft copolymer with the balance being furnished by the monomer which isgrafted and polymerized onto the nitrated backbone polymer. Thefollowing examples illustrate various embodiments of this invention andare to be considered not limitative.

EXAMPLE 1 Graft Copolymer of Methyl Methacrylate and 1,2-PolybutadieneInto a resin kettle equipped with a reflux condenser, a thermometer, amechanical stirrer, and a gas inlet tube were placed 50 g of1,2-polybutadiene (molecular weight 10,000) and diethyl ether (300 ml).The

mixture was stirred at room temperature until the polymer dissolved andthe solution was cooled to ice bath temperature while purging it withnitrogen (V2 hr). The gas inlet tube was connected to a graduatedcontainer of liquid dinitrogen tetroxide; a stream of nitrogen waspassed over the dinitrogen tetroxide and the resultant gaseous mixture(N O /N was conducted into the reaction solution (at ice bathtemperature) through the gas inlet tube. 0.4 ml of liquid dinitrogentetroxide was transferred to the reaction solution in this manner over aperiod of 55 min. Methyl methacrylate (25 ml) was added to the reactionsolution and the resultant solution was heated at 50-55 C for a periodof 5 hr. Most of the ether was distilled from the reaction mixturewithin the first hour of this time period. After stirring overnight atroom temperature the resultant solution was stirred into methanol (400ml). yielding the graft copolymer product as a precipitate. Therecovered product. which was dried in vacuo, weight 7.2 g.

Addition of a benzene solution of the graft copolymer to isopropylalcohol resulted in a hazy solution but most of the product remainedsoluble. In contrast. methyl methacrylate homopolymer immediatelyprecipitated when its solution in benzene was similarly added toisopropyl alcohol. This test indicated that a true graft copolymer hadbeen formed.

EXAMPLE ll Graft Copolymer of Butyl Methacrylate on NitratedEthylene/Propylene/S-Ethylidene-2-Norbornene Terpolymer Into a resinkettle equipped with a reflux condenser. a thermometer, a mechanicalstirrer, and a gas inlet tube were placed 5.0 g of anethylene/propropylene/S- ethylidene-2-norbornene terpolymer marketed byCopolymer Rubber and Chemical Corporation under EPsyn trademark Epsyn40-A (molecular weight 76.000. raw Mooney viscosity(ML-8' at 250F) 40.specific gravity 0.86, gel content none) and n-heptane 160 ml). Themixture was stirred at roomtemperature until the polymer dissolvedfollowing which the solution was cooled to the temperature of an icebath. The

gas inlet tube was connected to a graduated container of liquiddinitrogen tetroxide; a stream of nitrogen (at a rate of 60.8 ml/min(STP)) was passed over the dinitrogen tetroxide and the resultantgaseous mixture (N204/N2) was conducted into the reaction solution (atice bath temperature) through the gas inlet tube. Onetenth milliliter ofliquid dinitrogen tetroxide was transferred to the reaction solution inthis manner over a period of 47 min. Unreacted dinitrogen tetroxide waspurged from the reaction solution with a stream of nitrogen. Butylmethacrylate (50 ml) was added to the reaction solution andapproximately 90 ml of solvent was stripped off under vacuum toconcentrate the reactants. The reaction solution was subsequently heatedat about 60 and 80C for 2 and 4 hr, respectively. After dilution withbenzene (100 ml) to lower the viscosity and after methanol (400 ml) wasadded, the graft copolymer product precipitated from the solution. Tothe resulting mixture there was added 1500 ml of additional methanolwith mixing following which the graft copolymer was separated bydecantation. The product was dissolved in 200 ml of benzene andre-precipitated by addition of 1000 ml of methanol (to remove unreactedmonomer) and afterwards dried in vacuo. The weight of the dry polymerwas 18.1 g.

A sample of a graft copolymer product prepared with EPsyn 40,-A andbutyl methacrylate in the same manner as in Example ll (0.810 g),calculated to contain 0.25 g of EPsyn 40-A, was dissolved in benzene (30ml). Acetone ml) was slowly added to this solution resulting inprecipitation of an acetone-insoluble fraction amounting to 0.103 g. Asimilar procedure with 0.250 g of EPsyn 40-A resulted in precipitationof 0.228 g. In addition. an infrared spectrum of the acetone-insolublefraction of the product indicated that it contained an appreciableamount of polybutyl methacrylate which as a homopolymer isacetone-soluble. These tests indicate that a true graft copolymer hadbeen prepared.

EXAMPLE lll Nitrated 1,2-polybutadiene Into a resin kettle equipped witha reflux condenser, a thermometer, mechanical stirrer, and a gas inlettube are placed 5.0 g of l,2-polybutadiene (molecular weight about 4800)and carbon tetrachloride (300 ml). The polymer is dissolved by stirringthe mixture at room temperature after which the solution is purged withnitrogen hr). ln the next step the gas inlet tube is connected to agraduated container of liquid dinitrogen tetroxide. Nitrogen is passedover the liquid dinitrogen tetroxide and the resultant gaseous mixture(N O /N conducted into the reaction solution (at 28 C) through the gasinlet tube. In this manner, 0.4 ml of the liquid dinitrogen tetroxide isadded to the reaction solution over a period of about 60 min. Thenitrated polymer thus formed is recovered from the reaction mixture as asolid product after removal of the solvent by distillation. (Yield:about 5.3 g).'

EXAMPLE IV Nitrated Ethylene/4.4-Dimethyll -Hexene/5-Methylidene-2-Norbornene Terpolymer A total of 5.0 g of anethylene/4,4-dimethyl-lhexene/S-methylidene-2-norbornene' terpolymerhaving a molecular weight of 55,000 is added to a resin I kettleequipped with reflux condenser, a thermometer, a mechanical stirrer anda gas inlet tube and n-hexane ml). The mixture is stirred at about roomtemperature until the terpolymer dissolves following which the solutionis cooled to ice bath temperature. The gas inlet tube is connected to agraduated container of liquid dinitrogen tetroxide. Nitrogen gas at therate of about 40 ml/min (STP) is passed over the dinitrogen tetroxideand the gaseous mixture resulting (N O /N is conducted into the reactionsolution at ice bath temperature through the gas inlet tube. In thismanner, about 0.2 ml of liquid dinitrogen tetroxide is added to thereaction solution over a period of about 35 min. Unreacted dinitrogentetroxide is purged from the reaction solution utilizing a stream ofnitrogen after which the solvent is stripped from the reaction mixtureyielding the solid nitrated terpolymer. (Yield: approximately 5.1 g).

EXAMPLES V-Xl A number of additional graft polymerization runs wereconducted in the same manner as described in Examples l and ll above.Pertinent details relating to these examples are presented in Table l.

TABLE 1 Graft Copolymerization with Nitrated Ethylene/Propylene/5-Ethylidene-Z-Norbornene Terpolymer" In preparing thenitrated terpolynier 0.! ml (liquid) dinitrogen tetroxide was slowlytransferred as a gas mixed with nitrogen into a solution of 5.0 g of thebackbone polymer.

" Backbone terpolymcr. an ethylune/propylene/5-ethylidene-Z-norhorneneterpolymer marketed by (opolymer Rubber and Chemical Corporation underthe trademark Elsyn 5S. molecular weight about 90.600. raw Mooneyviscosity (ML-K at 50F) 55. specific gravity 0.86. gel content none).

" Backbone terpolynier EPsyn 40-.-\. (See Example II for description.)

EXAMPLES XllXlV In this series the grafting of butyl methacrylate.lauryl methacrylate and a mixture of lauryl methacrylate. and butylmethacrylate respectively, to anethylene/propylene/S-ethylidene-Z-norbornene terpolymer having amolecular weight of about 76.000 (EPsyn 40-A) was out cracking.Pertinent data relating to these tests are included in Table 3.

The lzod impact strength reported for film prepared with the polymer ofExample X is 12 times greater than that obtained for poly(methylmethacrylate) and is in the range exhibited for many commercialacrylonitrilebutadiene-styrene (ABS) resins.

TABLE 3 MECHANICAL PROPERTIES OF SOLID CRAFT COPOLYMERS (opolymer ofPoly-MMA /Epsyn 55 lzod Impact. Elastic Tensile Strength ElongationExample Weight Ratio ft lb per Modulus. at Break. psi

in Notch psi Poly-MMA 0.3 425,000 9750 9.5

Poly-MMA is poly(methyl methacrylate).

deomonstratedv The nitration step (first stage reaction) The graftcopolymers of this invention may be uti was conducted by stirring asolution of the polymer (9.4 weight percent in heptane) with dinitrogentetroxide (about 4.0 X 10' mole per gram of polymer) for- TABLE 2 lizedto prepare rod. sheet and parts such as horn buttons, instrument panelsand medallions. safety guards, brush backs, costume jewelry, decorativeparts, parts for home appliances, toys, reinforced plastics, etc. withhigh tensile and impact strengths, by extrusion or molding at pressuresranging from about 500 to 15,000 psi or more at temperatures of fromabout 100 to about 250C. Lubricants, plasticizers, modifiers, fillers,coloring matter may be added to the copolymer compositions as requiredas will be appreciated by those skilled in the art. In general, thegraft copolymers of this invention can be employed whereverimpact-resistant resins (e.g. ABS resins, high-impact polystyrene) arenow METHACRYLATE GRAFl' COPOLYMERS Graft Conditions Run No. MonomerTemp(C) Timc (hr) Conversion Polymer ('71') Weight lncreaseU/z) Xll BMAI00 7 l2.2 llO Xlll LMA 100 7 66 XIV LMA- 5 7.1 63

BMA

' BMA and LMA stand for hutyl and lauryl methacrylates. respectively. 2LMA-BMA molar ratio of 1.47:1.

used. When used in place of resin containing SBR or nitrile rubbers.they yield products with improved aging and ozone resistance.

A smooth reinforced plastic sheeting composition possessing excellentmechanical properties can be prepared by mixing about parts by weight ofthe graft copolymer of Example ll and about 50 parts by weight of apolyvinyl butyral resin having a polyvinyl alcohol content not in excessof 22 percent. in a Banbury mixer for about minutes and then passing themixture through a three-roll vertical calender. This same compositioncan be formulated as a molding compound possessing the ability to bemolded by compression or injection on short cycles and at reasonabletemperatures.

The graft copolymers of this invention are useful for wire cablecovering. For example. clean copper wire (8 gage) can be passed througha bath containing a percent by weight solution of the copolymercomposition of Example X in benzene at a temperature of C and afterwardspassing the treated wire through a dryer maintained at 85C to yield aninsulated wire having a highly flexible copolymer coating useful in avariety of electrical applications.

What is claimed is:

l. A process for preparing a nitrated polymer which comprises:

A. contacting a backbone polymer having a saturated hydrocarbon chainportion and plurality of pendant hydrocarbon groups each containing amoiety of the formula:

wherein R and R" are independently selected from the group consisting ofhydrogen and alkyl of from l to 16 inclusive carbon atoms. withdinitrogen tetroxide at a temperature of about 30 to about 20C thusforming a nitrated backbone polymer product having incorporated thereinnitro and nitrite groups wherein the.

R -CR II C-Re l CH wherein R" and R are independently selected from thegroup consisting of hydrogen and alkyl of from 1 to 16 carbon atoms.

5. The process of claim 1 wherein the said backbone polymer is aterpolymer of ethylene, propylene and 5-ethylidene-2-norbornene.

6. The process of claim 1 wherein the said backbone polymer comprisesrecurring units of the formula:

wherein R" and R" are independently selected from the group consistingof hydrogen and alkyl of from 1 to l6 inclusive carbon atoms.

1. A PROCESS FOR PREPARING A NITRATED POLYMER WHICH COMPRISES: A.CONTACTING A BACKBONE POLYMER HAVING A SATURATED HYDROCARBON CHAINPORTION AND PLURALITY OF PENDANT HYDROCARBON GROUPS EACH CONTAINING AMOIETY OF THE FORMULA:
 1. A process for preparing a nitrated polymerwhich comprises: A. contacting a backbone polymer having a saturatedhydrocarbon chain portion and plurality of pendant hydrocarbon groupseach containing a moiety of the formula:
 2. The process of claim 1wherein the backbone polymer comprises recurring units of the formula:3. The process of claim 1 wherein the said backbone polymer is1,2-polybutadiene.
 4. The process of claim 1 wherein the said backbonepolymer is a terpolymer of ethylene, propylene and units of the formula:5. The process of claim 1 wherein the said backbone polymer is aterpolymer of ethylene, propylene and 5-ethylidene-2-norbornene.